Abstract
Glutamic acid decarboxylase (GAD) antibodies are associated with disabling conditions such as stiff person syndrome, temporal lobe epilepsy (TLE), limbic encephalitis, cerebellar ataxia (CA), and ocular movement disorders, which are usually chronic and difficult to treat. GAD-related TLE has poor response to anti-seizure medications and immune therapies, and epilepsy surgery is rarely successful. We report on a 47-year-old female with history of migraine, autoimmune thyroid disease, ankylosing spondylitis, and drug-resistant TLE. A video electroencephalography recorded frequent seizures with temporo-insular semiology, correlating to left temporal epileptiform activity and left mesiotemporal hyperintensity on magnetic resonance imaging. GAD autoimmunity was confirmed by very high GAD antibody titers in serum and cerebrospinal fluid. Steroids, immunoglobulins, and cyclophosphamide had no effect, and selective left amygdalectomy was performed based on very restricted hypermetabolism on positron-emission tomography. After transient seizure freedom, significant epilepsy improvement was observed in spite of memory decline. Transient worsening was noted 1 year later during diabetes mellitus manifestation and 5 years later during presentation of progressive CA, which stabilized on rituximab treatment. We believe this case illustrates the diversity and the frequent overlap of GAD-associated disorders, the need of early and aggressive immunotherapy in severe patients, as well as the possible benefit from epilepsy surgery in some GAD-TLE.
Highlights
Glutamic acid decarboxylase antibodies (GAD-Abs; against the enzyme isoform GAD65) are usually associated with chronic conditions, increasingly recognized during the last three decades
GAD-Ab association must be suspected in cases with no obvious cause of temporal lobe epilepsy (TLE), and it has been postulated that GAD-Ab need to be found in high serum titers or to be detected in cerebrospinal fluid (CSF) to prove the causal relationship [1, 2, 4, 6, 7]
A very high GAD-Ab titer was found both in serum and CSF, where the recognized abnormal level is >1,000 IU/ml by ELISA [2], and similar to previous reports, the serum level was much higher than that in CSF [7, 8]
Summary
Glutamic acid decarboxylase antibodies (GAD-Abs; against the enzyme isoform GAD65) are usually associated with chronic conditions, increasingly recognized during the last three decades. 4 years after the operation, rare episodes of dizziness and falls were reported and interpreted by the patient as probable seizures They were not recorded on VEEG, but right temporal epileptiform activity was registered, and lacosamide (LCM) was added. Further decrease in seizure frequency to two per month was observed as well, but due to the locomotor and distal limb ataxia at present, the 47-year-old woman is independent and able to fulfill her usual activities at home only. Neuropsychological testing before, 6 months after and most recently, 4.5 years after surgery, demonstrated significant worsening of the memory function from mild short-term verbal memory deficit prior to the selective left amygdalectomy to marked verbal and FIGURE 3 | (A) Axial FLAIR MRI with left HS (red arrow).
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